seems like Dual Mining doesn't work with 5 or more 480 cards as the system will reboot itself after a minute.
It's draining power more than mobo can supply even with powered USB riser.
I have a 1200w psu & after a few minutes, it's still crash with just 5 cards slotted in.
hmm this is a huge post, I seem to have killed two MSI gaming 5 motherboards trying to fit six cards dual mining on them.
ALL cards were hooked up USB powered risers, both boards worked fine with 5 cards and then i dicided to consolidate a few other new cards on these boards and poof dead Motherboard after a few reboots like you expereinced, Stupid me I should have realized something was off when the same rig that had worked fine since the 1st of July suddenly started having issues. I've been dual mining DCR from the start so I dont think its an issue with SIA.
Word to the wise only use 5 cards max if with these new cards.
I have another six card rig i set up this morning dual mining i hope i dont come home to another dead board I only have one more spare.
Did u undervolt the RX480 or not? With core and mem @900 mv there is no way you killed motherboard because of RX480 ,i mean at 0.900 VDDC the card will take 70-80W total power,means 35-40-45 max from pci-e slot...